Abstract
Arylsulfatase A activity has been determined quantitatively in leukocytes of two unrelated patients with late adult metachromatic leukodystrophy (MLD) (40 and 44 years old) and 29 family members. A differentiation between homozygote patients, heterozygote carriers, and persons with a normal enzyme activity is possible. A profound enzyme deficiency has also been detected in three so far healthy persons (13, 39, and 40 years old). It is supposed that they are in the preclinical state of the disease. Using the common applied technique of arylsulfatase determination, the extent of the enzyme defect in the manifestly affected patients is not significantly different from that of the infantile form of MLD.